An Internet Protocol (IP) multimedia subsystem (IMS) is a network system that provides voice and multimedia services based on an IP network. In an IMS network, as a calling number, an IP multimedia public identity (IMPU) may correspond to a user having at least one terminal, that is, one IMPU may correspond to multiple terminals, and one terminal may correspond to multiple IMPUs. In the IMS network, multiple terminals corresponding to an IMPU may be called by using the IMPU. The terminal herein may be an intelligent communications module in the IMS network, and generally is a telephone card, for example, a subscriber identity module, a universal integrated circuit card, or a universal subscriber identity module. An international mobile subscriber identity (IMSI) may uniquely identify a telephone card, but the IMSI cannot be used as a calling number in the IMS network. To call a particular terminal in at least one terminal corresponding to the IMPU, a globally routable user agent uniform resource identifier (GRUU) is introduced in the IMS system. When registered in the IMS network, each terminal is allocated one unique calling number GRUU. Therefore, a terminal identified by a GRUU may be called uniquely by calling the GRUU in the IMS network. The GRUU includes an IMPU and an international mobile equipment identity (IMEI). An IMEI uniquely identifies single card user equipment having only one card slot, that is, single card user equipment into which only one telephone card can be inserted. When user equipment has multiple card slots, an IMEI uniquely identifies one card slot.
In addition to normal services such as phone call, short message service, and fax, the IP-based voice services provided by the IMS system may further include supplementary services such as call transfer, call barring, and call waiting. When a user configures a supplementary service, the user may send a supplementary service configuration request to a server in the IMS network, for example, a telephone application service, to configure a supplementary service corresponding to a GRUU. The telephony application server saves the supplementary service configured by the user in the supplementary service configuration request. For example, the supplementary service configured by the user may be barring a call from GRUU-1, that is, barring a call from a telephone card identified by GRUU-1. When an IMPU does not change, because an IMEI in a GRUU corresponds to a card slot, when a card slot into which a telephone card is inserted changes, a GRUU obtained after registration is performed in the IMS network by using the telephone card also changes, that is, a correspondence between the telephone card and the GRUU changes. In this way, an error may occur in a correspondence between the supplementary service that corresponds to the GRUU and that is saved in the telephony application server and the telephone card, causing an error to the supplementary service of the telephone card.